Racer Brown ST-21

I think compression target guidelines are somewhat misleading. Saying this cam needs to have X compression or it won't work well, it doesn't tell the whole story.

No big cam is gonna be great down low. Poor idle quality and off idle response, low vacuum levels, etc. Having lower compression makes it worse.

In terms of power output, as long as you're in normal ranges I believe you're fine. If we could afford race fuel all the time we'd be running 14:1 compression but $30/gal isn't practical.

Compression will raise or lower the curve that the cam produces. Higher compression will give you more power. Great. But if your current engine "only" has 9:1, it'll still be fine and make good power. Just not as much. Good thing is pump gas should never be a problem though.

If you care enough, Richard holdener did a test specifically on this point, where he tested the same combo at several compression levels. Guess what the 8:1 big cammed motor still made good power. Not as much but the dyno curves proved the point.